Gas barrier during edge rinse of SOG coating process to prevent SOG hump formation

Abstract

A method and an apparatus are disclosed for preventing the formation of humps along the edge of substrates while being spin coated. Said humps are especially observed in edge rinsing substrates that are being coated with spin-on-glass (SOG) and state of the art photoresists. The edge rinse is usually directed at the edge of the substrate at a certain angle from the vertical axis of the rotating substrate. The hump is a consequence of the phenomenon of hydraulic jump that occurs in fluid flow. The humps, later in the manufacturing process, disintegrate causing particle contamination problems. A novel technique is proposed where the formation of humps is prevented by directing a jet stream of gas at the hump. The jet is placed along the plane of the spinning substrate, and behind the rinse nozzle in the direction of the spin.

What is claimed is: 
     
       1. A spin coating method comprising the steps of: providing a substrate on a turntable;   dispensing a film forming material over said substrate;   rotating said turntable;   forming a film of coating of said film forming material over said substrate;   rinsing said film of coating at its outer edge; and   impinging said film at its outer edge with a jet stream of a gas that is inert to said film issuing towards the outer edge of said substrate and following said rinsing.   
     
     
       2. The method of claim 1, wherein said substrate is silicon wafer. 
     
     
       3. The method of claim 1, wherein said wafer is secured on to said turntable by means of vacuum suction. 
     
     
       4. The method of claim 1, wherein said film forming material is spin-on-glass (SOG). 
     
     
       5. The method of claim 1, wherein said film forming material is photoresist. 
     
     
       6. The method of claim 1, wherein said dispensing is accomplished by means of a dispense nozzle. 
     
     
       7. The method of claim 6, wherein said dispense nozzle is placed centrally over said substrate. 
     
     
       8. The method of claim 1, wherein said turntable rotates between about 1000 rpm to 3000 rpm. 
     
     
       9. The method of claim 1, wherein said film of coating is formed to the edge of said substrate. 
     
     
       10. The method of claim 1, wherein said rinsing is accomplished by means of a rinse nozzle. 
     
     
       11. The method of claim 10, wherein said rinse nozzle is directed at edge of said substrate. 
     
     
       12. The method of claim 11, wherein said rinse nozzle forms an angle of between about 37.5° to 52.5° with the vertical axis of said turntable. 
     
     
       13. The method of claim 10, wherein said impinging is with a jet stream nozzle placed parallel to the surface of and radially from the center of said substrate. 
     
     
       14. The method of claim 13, wherein said jet stream nozzle is positioned between about 15° and 90° behind said rinse nozzle measured from the center of said turntable and in the direction of rotation of said turntable. 
     
     
       15. The method of claim 14, wherein said jet stream is nitrogen gas. 
     
     
       16. The method of claim 15, wherein said jet stream is issued with a pressure between about 550 kPa to 650 kPa. 
     
     
       17. The method of claim 1, wherein said rinsing is accomplished with cleaning liquid isopropyl alcohol. 
     
     
       18. The method of claim 17, wherein said cleaning liquid is issued with a pressure between about 47.5 kPa to 52.5 kPa. 
     
     
       19. The method of claim 1, wherein said impinging with a jet stream is accomplished with a nozzle. 
     
     
       20. A spin coating apparatus comprising: a substrate;   a turntable;   a means for holding said substrate;   a dispense nozzle above said turntable;   an edge rinse nozzle above and at the edge of said turntable; and   a jet stream nozzle following said edge rinse nozzle.   
     
     
       21. The apparatus of claim 20, wherein means for holding said substrate on said turntable is vacuum suction. 
     
     
       22. The apparatus of claim 20, wherein said dispense nozzle is placed centrally and above with respect to said turntable. 
     
     
       23. The apparatus of claim 20, wherein said edge rinse nozzle forms an angle of between about 37.5° to 52.5° with the vertical axis of said turntable. 
     
     
       24. The apparatus of claim 20, wherein said jet stream nozzle is placed parallel to the surface of and radially from the center of said substrate. 
     
     
       25. The apparatus of claim 24, wherein said jet stream nozzle is positioned between about 15° and 90° behind said rinse nozzle measured from the center of said turntable and in the direction of rotation of said turntable.